The present invention relates to an intake valve control apparatus for an internal combustion engine, which comprises a first variable valve operating mechanism capable of varying an operation angle of an intake valve and a second variable valve operating mechanism capable of varying a maximum lift phase of an intake valve (a phase at which the lift of the intake valve becomes maximum or a center phase of an operation angle). The present invention further relates to an intake valve control method.
In a gasoline engine, an intake air amount is usually controlled by controlling an opening degree of a throttle valve disposed in an intake passage. However, as is well known, such a method is encountered by a problem that a large pumping loss is caused particularly at the time of a small opening degree of the throttle valve, i.e., at a low-to-middle load engine operating condition. To solve this problem, it has been tried to control the intake air amount by controlling the opening and closing timings and lift of the intake valve, without depending upon the control by the throttle valve.
An intake valve control apparatus consisting of a first variable valve operating mechanism (lift and operation angle varying mechanism) capable of varying a lift and operation angle simultaneously and continuously and a second variable valve operating mechanism (phase varying mechanism) capable of varying a maximum lift phase continuously and adapted to control the intake air amount by mainly varying the opening and closing timings of the intake valve is disclosed in Unexamined Japanese Patent Publication No. 2002-256905.
In such an intake valve control apparatus, the variable valve operating mechanisms are supplied with control target values in accordance with an engine operating condition and controlled based thereon.